Process and composition for dissolving copper oxide

ABSTRACT

The present invention relates to dissolving copper oxide, whether cuprous or cupric oxide. A polyamine selected from a group consisting of ethylenediamine, diethylenetriamine, triethylenetetramine and tetraethylenepentamine is mixed with a compound selected from a second group consisting of salicyclic acid, metahydroxybenzoic acid, parahydroxybenzoic acid, a dihydroxybenzoic acid, 5-5&#39;&#39;-methylenedisalicyclic acid, 3hydroxy-2-naphthoic acid and salts thereof with an aliphatic polyamine of the first class and with ammonium hydroxide in an alkaline water solution or a salicylate of one of these amines can be used with ammonium hydroxide. The composition can be used cold but will preferably be used in a temperature range between 150* F. and the boiling temperature at the particular pressure.

United States Patent 1151 3,637,508 Willsey et al. 1 1 Jan. 25, 1972 541PROCESS AND COMPOSITION FOR 3,173,876 3/1965 Zobrist ..252/152DISSOLVING COPPER OXIDE 3,218,351 11/1965 Jolly .252/152 3,248,2354/1966 Pryor et al. 106/3 Inventors: William B. Willsey, 108 DeerfieldDrive, Cherry Hill, NJ. 08034; Daniel J. Brogan, 7111 Penarth Ave.,Upper Darby, Pa. 19082 Filed: Mar. 6, 1970 Appl. No.: 17,154

Related US. Application Data [63] Continuationin-part of Ser. No.601,181, Dec. 12,

1966, abandoned.

[56] References Cited UNITED STATES PATENTS 3,003,970 10/1961 Call..252/152 Primary Examiner Richard D. Lovering Assistant ExaminerlrwinGluck Att0rneyJackson, Jackson & Chovanes The present invention relatesto dissolving copper oxide, whether cuprous or cupric oxide. A polyamineselected from a group consisting of ethylenediamine, diethylenetriamine,triethylenetetramine and tetraethylenepentamine is mixed with a compoundselected from a second group consisting of salicyclic acid,metahydroxybenzoic acid, parahydroxybenzoic acid, a dihydroxybenzoicacid, 5-5-methylenedisalicyclic acid, 3-hydroxy-2-naphthoic acid andsalts thereof with an aliphatic polyamine of the first class and withammonium hydroxide in an alkaline water solution or a salicylate of oneof these amines can be used with ammonium hydroxide. The composition canbe used cold but will preferably be used in a temperature range between150 F. and the boiling temperature at the particular pressure.

ABSTRACT 17 Claims, 12 Drawing Figures CuO S0 LUB LE, gms.

PATENTEU JAN 2 51972 3.637.508 SHEET UlUF 12 CONDITIONS l gm. CuO

06 5hrs TIME 6.75 gms. ETHYLENEDIAMINE Q5 42-5 gms. WATER 3 -4 5SALICYLIC ACID, gms.

CuO SOLUBLE,gms.

PATENIEDJANZSISYZ 3,637508 SHEET OEUF 12 iZg /a.

CONDITIONS I gm. CuO

42.5 gms. WATER 5hrs. TIME 6.75gms. ETHYLENEDIAMINE I 1 I I I I l l l lI l l I J l I 2 8 I0 I I2 I4 WEIGHT RATIO ETHYLENEDIAMINE TO SALICYLICACID 7. ATTORNEYS PATENTEUJM25IQY2 3.637.508

SHEET 614 OF 12 Fig.3.

CONDITIONS 1.0- lgm. CuO

425 gms. WATER 5 hrs. TIME 200 F.

- 6.75 gms. ETHYLENEDIAMINE gms.

CuO SOLUBLE I I I l l I I l l I I l I I I I l 2 4 e 8 l0 l2 l4 WEIGHTRATIO ETHYLENEDIAMINE TO SALICYLIC ACID SODIUM SALT ATTORNEYSPATENTEDJANZSBFZ 3.637.508.

CONDITIONS I gm CuO 0.9- 42.5 gm s. WATER 5hrs.TlME

200 F. 6.75gms. ETHYLENEDIAMINE 0.6 g L 1 30.5- CD 3 .J 0 (00-4;

I l l I l I 1 l l 1 l l l I 2 4 e 8 l0 l2 :4 WEIGHT RATIOETHYLENEDIAMINE TO ETHYLENEDIAMINE SALICYLATE INV TORS Mai/(4745.114! 5fimwe/J fira zm MQWQQ ATTORNEYS SHEET 08 0F 12 Z/ gZZ CONDITIONS lgm.CuO 0.9 42.5 gms. WATER 5hrs- TIME 6.75gms. ETHYLENEDIAMINE CuO SOLUBLE,gms. p O a v1 1 1 1 1 1 1 1 1 1 1 1 l 1 1 1 1 2 4 6 8 IO l2 l4 WEIGHTRATIO ETHYLENEDIAMINE TO 3-'HYDROXY2'-NAPHTHO|C ACID ATTORNVEYS CuOSOLUBLE, gms.

PATENTEU Jms If}? 3,637. 508 SHEET 09 0F 12 CONDITIONS lgm. CuO

0.9 425 gms, WATER 5 hrs. TIME 200 F. 6-75 gms. ETHYLENEDIAMINE l I l 1l l I l 1 1 I 2 4 s 8 IO I2 I4 WEIGHT RATIO ETH YLENEDIAMINE TOI-HYDROXY-ZNAPHTHOIC ACID flarzze/ 670 m PATENYEU JAMES [9?2 SHEET 10 U?5.0 gms. SALICYLIC ACID E W M m D E N S A T N W E m s &

Ds o

O Q. 2 O 7.

A 5 TIME, HOURS 7; .2

m .25 QED-6m 03 n B O Mai/4am VEly/ RS & may Warns/6794 BY r" V \k gATTORNEYS CuO SOLUBLE gms.

PATENTEDJmsmz 3,637,508

SHEET 11 0F .2

CONDITIONS LOgm. CuO/50gms. SOLUTION 200F 5 hrs. TIME CONSTANT WEIGHTRATIO gms. ETHYLENEDIAMINE gms, SALICYLIC ACID l I I I l I I J I I I I II I I 4 6 B IO I2 l4 'ETHYLENEDIAMINE '/o BY WEIGHT 1 VENT xs 14444224:a BY flazwe/Jfirgyaa ATTORNEYS The solution used can be static orcirculating although circulation improves the results. The solution canalso be used as a foam with a suitable gas as described in Brenner etal. US. Pat. No. 3,037,887, granted June 5, 1962, for Foam Cleaning ofSurface and in Carroll et al. US. Pat. No. 3,212,762, granted Oct. 12,1965 for Pump Generator. if the equipment lends itself to pressure or toreflux condensation, this can be used. The addition of foaming agentpermits a sevento thirtyfold increase in volume, so that a large spacemay be filled with a minimum amount of the solvent.

If corrosion of the underlying copper can be tolerated, such as inpreparation for silver plating, the rate of copper oxide dissolution canbe accelerated by adding an oxidizing agent such as ammoniumpersulphate.

The process of the invention can be employed effectively to removecuprous oxide, but it is even more effective on cupric oxide and ascupric oxide is more frequently encountered, the test results arechiefly directed to removal of cupric oxide.

Wide variations in concentration can be employed but preferably theconcentration of combined ethylenediamine or the like and salicylic acidor the like should be between 0.25 and 100 percent by weight, mostdesirably between 1 and 50 percent by weight, and under normalconditions concentrations of the order of l5 to 30 percent by weight,the balance in any case being a solvent such as water.

The weight ratio of ethylenediamine or the like to salicylic acid or thelike should preferably be between about 0.25 and 6, more desirablybetween 0.50 and 4 and most desirably about 1.4 although if desiredgreater ratios may be used, with diminishing effectiveness. In otherwords, it is preferable to have about 3 moles of ethylenediamine to 1mole of salicylic acid.

For many purposes, the composition of the invention will includeethylenediamine, salicylic acid and water. Instead of ethylenediamine,however, other aliphatic polyamines may be used, examples of such otherpolyamines being diethylenetriamine, triethylenetetramine andtetraethylenepentamine.

Salicylic acid is of course orthohydroxybenzoic acid. As altematives forsalicylic acid, metahydroxybenzoic and parahydroxybenzoic acids may beused.

A dihydroxybenzoic acid can also be employed instead of salicylic acid,an example being 2,4-dihydroxybenzoic acid. A disalicyclic acid may alsobe employed, an example being 5,5 methylenedisalicylic acid which alsois known as 4,4- dihydroxydiphenylmethane-3,3 '-dicarboxylic acid.

3-hydroxy-2-naphthoic acid can be used instead of salicylic acid but onthe other hand l-hydroxy-Z-naphthoic acid is not effective, apparentlybecause of the different location of the double bond.

Any one of the acids above referred to can be used in the form of saltswith ethylenediamine, diethylenetriamine, triethylenetetramine andtetraethylenepentamine or ammonium hydroxide. Examples areethylenediamine salicylate, diethylenetriamine salicylate, ammoniumsalicylate, and the ethylenediamine salt of parahydroxybenzoic acid. Aslater explained in more detail, however, salts of these acids withmetals such as sodium or potassium, of which an example is sodiumsalicylate, are not effective.

In any one of the cases given above, the particular alternate compoundcan be used in admixture with the compound for which it is substituting,as for example salicylic acid can be used mixed with parahydroxybenzoicacid.

A salicylate of ethylenediamine or one of the other aliphatic polyaminesreferred to with sufficient ammonium hydroxide to maintain thecombination alkaline is an effective composition for dissolving copperoxide and shows to a substantial extent the unusual properties abovereferred to.

It will be evident that all of the resultant compositions of the presentinvention in water solutions are inherently alkaline by virtue of thestrongly alkaline character of the polyamines.

Because salicylic acid and the other hydroxy-substituted compounds arestrictly organic in nature, their chemical properties are vastlydifferent from the inorganic hydroxyl amine mineral acid salts used inthe Call composition previously referred to.

Hydroxylamine-type compounds have pronounced oxidation-reductionproperties whereas the oxidation-reduction properties of salicylic acidand the other related compounds disclosed by applicants are negligible.An example of this pronounced oxidation-reduction property ofhydroxylamine and its salts is that they will react quite vigorouslywith ferrous ions. The ferrous ion is oxidized to ferric ion and thereaction is accompanied by an undesired excessive exothermic heat ofreaction. lf cupric ions are present, they are reduced to cuprous ionsor metallic copper which will plate out on metallic and other surfaces.

Not only does the use of salicylic acid or the related compoundsdisclosed by applicants in combination with ethylenediamine greatlyenhance copper oxide solubility, but none of the previously referred toundesirable reactions will occur when ferrous ions are present.

Since the compositions of this invention essentially do not react withferrous or ferric ions, the corrosion rate for iron, steel and stainlesssteel is much lower. Also, since the compositions do not reactcorrosively with iron, the solution may be prepared in an ordinary steeltank. This contrasts with Calls solvent which must be prepared in aplastic-lined tank because it will react violently with iron oxides thatmay be present in a steel tank.

The theoretical explanation of the remarkable synergism illustrated bythe composition of the invention seems to be due to the fact that thesalicylic acid reacts with ethylenediamine or the equivalent and theresulting compound is much more effective in dissolving copper oxidethan either of the original components. In some cases at least thereaction appears to involve two molecules of salicylic acid reactingwith one molecule of ethylenediamine, although in other cases reactionmay be in different molecular proportions.

The copper oxide solubility of the compositions of this invention is dueto:

l. The copper forms a water soluble complex with the salicylic acid typecompound. The complex formed is illustrated below.

H alkaline /CO aqueous O OH solution Cu++ Cu 1110 2. If p-hydroxybenzoicacid is used, the separation of the positions of the OH and COOl-l'groups are too great for the above complex to be formed and thefollowing reaction occurs:

One gram of reagent grade cupric oxide (wire) was placed in an aqueoussolution having a volume of 50 ml. in which the amounts and ration ofethylenediamine and salicylic acid were varied. The solution was held incontact with the cupric oxide at F. for 5 hours. At the end of theexperiment any undis- PROCESS AND COMPOSITION FOR DISSOLVING COPPEROXIDE This application is a continuation-in-part of our copendingapplication, Ser. No. 601,181, filed Dec. 12, 1966 and now abandoned forProcess and Composition for Dissolving Copper Oxide.

The present invention relates to processes for dissolving copper oxide,whether cuprous or cupric oxide, and compositions therefor.

A purpose of the invention is to remove copper oxide by a compositionwhich is not inherently hazardous and therefore much safer than some ofthe compositions commonly used for this purpose.

A further purpose is to remove copper oxide without leaving any residueexcept for a small quantity of soluble copper salt which can be removedby washing with water.

A further purpose is to reduce the cost of the chemicals required.

A further purpose is to reduce the corrosion rate, especially on copperand copper alloys when removing copper oxide.

A further purpose is to employ a composition for removing copper oxidewhich will not react with iron or iron compounds.

A further purpose is to avoid objectionable gassing which in some casesin the prior art has produced an explosive type of overflowing.

A further purpose is to employ a solution for removing copper oxidewhich has insignificant exothermic heat of solutron.

A further purpose is to avoid plating or depositing copper by a solutionwhich has removed copper oxide.

A further purpose is to produce a bright passivated metal surface oncopper and copper alloys which is resistant to further oxidation.

Further purposes appear in the specification and in the claims.

The drawings show curves useful in explaining the inventron.

Copper may be picked up and carried by water or steam in a steampowerplant and deposited as copper oxide on buckets and nozzles of steamturbines, heat exchangers and condensers. It tends to reduce theefficiency of the equipment and therefore must be removed periodically.

This problem is most serious in supercritical turbines and boilers.Copper oxide is present in a vapor phase in high-pressure areas andtends to deposit at lower pressure locations on parts of the steamturbine.

Copper oxide also is a problem in feed water heaters for boilers.

There is also a need to remove copper oxide more effectively from coppercatalysts in oxidation bombs used for testing oil.

Particularly in the electrical industry, these are numerous requirementsfor cleaning copper or copper alloys, particularly prior to silverplating of contacts.

In the prior art, an effective manner of removing copper oxide is bydissolving it in a solution of hydroxylamine salt plus an aliphaticpolyamine such as ethylenediamine in water, according to Call U.S. Pat.No. 3,003,970, granted Oct. 10, 1961, for Cleaning Composition andMethod of Its Use. This has been employed extensively in cleaning steamturbines to remove copper oxide deposits.

ln employing the process of the Call patent, the following difficultieshave developed:

1. The composition reacts with iron and iron oxide and increases thecorrosion rate on steel, brass and other copper alloys, and this isobjectionable.

2. The composition of the Call patent when it reacts with iron and ironoxide present, produces violent gassing which may cause it to erupt froma tank or the like with a sort of violent expulsion or explosion.

3. The reaction with iron causes rapid development of exothermic heatcausing an objectionable rise in temperature.

4. When iron reacts with the Call composition, the corrosion rate onsteel and brass or other copper alloys is greatly increased.

5. When iron reacts with the Call composition, it tends to plate outcopper and this is objectionable.

The use of the Call solution and some of its difficulties are discussedby E. B. Morris and R. G. Call, Chemical Cleaning of Turbines forRemoval of Copper Oxide Deposits," ASME Publication 64-WA/BFS-l.

Among the other prior art compositions are those of Jolly U.S. Pat. No.3,218,351 which involves a mixture of salicylic acid and a very viscouswater-immiscible high molecular weight resin or fatty acid polyamine,and McCoy U.S. Pat. No. 2,540,003, and Holman U.S. Pat. No. 2,700,654,both of which involve the use of ethylenediamine with fatty acids, fattyacid esters, etc. Zobrist U.S. Pat. No. 3,173,876 shows the use ofethylenediamine with an enhancer such as sodium borate or a sodiumphosphate. Fatty acid compositions are expensive and difficult to use asthey may leave deposits.

The present invention is concerned with overcoming the difficultiespresent in the prior art compositions and particularly eliminating theabove difficulties referred to in connection with the Call composition.

The composition of the present invention is inherently not hazardous andis safe to use unlike some of the prior art compositions. It does notdissolve iron or iron oxide and does not undergo any gassing or violentreaction with iron or iron oxide. No substantial exothermic temperaturerise occurs during use.

The composition of the present invention does not have an increasedcorrosion rate on steel and brass from presence of iron.

There is no tendency to plate out copper using the solution of theinvention.

The composition of the invention can simply be used at low temperaturefor cleaning or polishing copper or copper alloys, and it is quiteeffective without the difficulties of the prior art compositions usedfor these purposes such as conventional bright dips.

The composition of the invention leaves no residue except a small amountof soluble copper salt which can be removed by washing with water.

The composition of the present invention avoids disassembly ofequipment.

The process and composition of the invention is less costly than theprior art compositions.

One of the elements in the low cost is not only that the chemicalsthemselves are inexpensive but also that the synergistic action greatlyreduces the quantity of chemicals required. This an an example, todissolve 0.45 grams of cupric oxide took 6.75 grams of ethylenediaminealong, but this same quantity of cupric oxide was dissolved by 1.5 gramsof ethylenediamine and 1.0 gram of salicylic acid used together.

One favorable result of the composition of the invention is that itleaves the surface of copper alloys passivated and resistant to furtheroxidation.

It is believed that the widest use of the invention may be in removingcopper oxide from the interiors of closed steam generators andassociated equipment such as steam turbines, heat exchangers, andcondensers. For this use it is best to employ the solution of theinvention at a temperature between F. and the boiling point of thesolution at the particular pressure. The reason for this is that theaction under these circumstances would be much slower if the solutionwere used cold.

It will also be decidedly preferable to use the solution thus heated incleaning copper catalysts in oxidation bombs for testing oils. in manycases, however, for general cleaning and polishing, effective resultswill be obtained by using the solution cold. One example is the removalof copper oxide from copper and copper alloys prior to silver platingcontacts.

The cleaning action in a cold solution can be accelerated by placing theparts on an ultrasonic vibration table in a cleaning bath.

recent cleaning the solvent action was accelerated by forcefullycirculating the composition at approximately 100 gallons per minute,whereas the original cleaning comprised a static soaking in the samecomposition. The increased rate of copper oxide removal is evidentlyattributable to the forced circulation of the composition. 7

To improve the heat transfer performance of the main steam turbinecondenser of a l82-megawatt generating unit, the inside of the tubing(water side) was cleaned by the foaming technique previously mentioned.A Spercent solution of inhibited hydrochloric acid foam at a 13 to 1foam-to-liquid ratio was passed through the condenser tubes, followed bya water foam, then by a foam solution of composition 23 at afoam-to-liquid ratio of 9 to l. and finally by a water foam. The outsideof the tubing (steam side) was sprayed with a 3 percent solution ofinhibited hydrochloric acid, followed by a spray of composition 23, andthen a water rinse, which left the metal surface in a bright passivatedcondition, resistant to oxidation. The entire procedure was carried outat a temperature of about 120 F.

Experiments were carried on in cleaning brass washers with thiscomposition in comparison with a conventional bright dip comprising anaqueous solution of 56 percent by weight of concentrated sulfuric acid,8.8 percent by weight of concentrated nitric acid and 0.2 percent byweight of concentrated hydrochloric acid. Copper plate was also cleanedin the solution and in the bright dip. These comparison were made atroom temperature. The solution of the present invention was about equalin effectiveness to that of the bright dip, without the use of theinherently hazardous materials comprising the latter.

Pieces after cleaning with the composition of the present in-' ventionand with the bright dip were treated in a mercury strike, were rinsed inwater and were then silver plated for half an hour. Visual examinationindicated the plating on all of the pieces was of equal quality and ontesting by scraping, the adhesion was about equal. The thicknesses ofsilver plating, as measured with a micrometer, on the brass washers andthe copper plate cleaned by the treatment according to the presentinvention were determined to be satisfactory and about the same as whenusing the bright dip. The costs of equal volumes of the composition ofthe present invention and the above bright dip were substantiallyidentical.

The composition of the present invention has the important advantageover conventional bright dips in that it may be used without thenecessity for the special precautions required for the safe use of thestrong acids comprised in the bright dips. Accordingly, the compositionof the present invention may be applied freely with a brush or as a washor spray to vertical and under surfaces of permanent structures, orwherever else bright dips could not be used because of the hazard.

Mixed with a mild abrasive such as powdered alumina, cream of tartar,precipitated chalk, or powdered magnesium carbonate, together with aconventional thickening agent such as starch, tapioca, gum tragacanth,gum dammar, gum arabic and the like to form a paste, the composition ofthe invention may be used as a household polish and cleaner for copperand brass. A suitable biocide may be incorporated if desired.

Copper switch parts were cleaned with the solution discussed inconnection with FIG. 10 for 5 to l0 minutes at room temperature and at lF. Good results were obtained in all cases but the parts treated atelevated temperatures were shiny and those treated at room temperaturehad a matte finish.

FIG. 11 plots cupric oxide soluble in grams as ordinate against time asabscissa for various temperatures shown by various curves as follows;

In each case a l-gram sample of cupric oxide was introduced into 50 ml.of composition 23.

It will be evident that the ability to dissolve cupric oxide increasesrapidly with temperature so that for example as much cupric oxide can bedissolved by the composition in 1 hour at 21 2 F. as can be dissolved in6 hours at 175 F.

Comparative tests were made using various amines and various acids oracid salts together, and also in some instances using amines or acidsalts along.

In each of these tests, 1 gram of reagent grade cupric oxide was placedin 52 grams of a solution consisting of one or more chemicals as listedplus water as a solvent, and the solution was maintained at 200 F. for 5hours. After the end of the 5 hour test period, the remaining cupricoxide was washed, dried, and reweighed to determine the amount of cupricoxide dissolved. The following table gives the quantities of reagentsused and the test results obtained:

QUANTITY OF CUIRIC OXIDE DISSOLVED BY SOLUTIONS HAVING REAUENTS NO'IEI)Weight Weight percent ol percent. of Solution Compo- Compo- Cupric oxideNumber Component A nent A Compooent B nent; B (IISSOlVtd 13. 7 None 45.0 12. 4 o-Hydroxybenzoic acid 9. 2 .19.9 12. 4 m-Hydroxybenzoic acid U.2 96. 6 12. 4 p-Hydroxybenzoic acid 9. 2 84. 2 14.1 None 53. 3 12. 8o-Hydroxybenzoie acid 9. 0 89. 8 12. 8 m-Hydroxybenzoic 301d... 1). 08S). 0 12.8 p-Hydroxybenzoic acid- J. 0 85. 6 14.7 None 57.6 13. 4o-Hycroxybenzolc acid 9. 1 86.0 13. 4 m-Hydroxybenzoie acid... 9.1 85. 413. 4 pHydroxybenzoie acid- 0. 1 83. 4 15.0 None 411.1 13. 6o-Hyc'lroxybenzoic acid 9. 1 85.1 13. 6 m'Hydroxybenzoic aG1d-..--. 9. 179.1 13. 6 p-Hydroxybenzoie acid... 9.1 84. 4 12. 4 Sodium salicylate 9.2 59. 7 12. 4 Ammonium salicylatefl nn 9. 2 U9. 8 12. 42,4-dihydroxybenzoie acid-.. J. 2 88. 2 12.4 1 hydroxy-2-maphthoic acid..1. 2 31.4 12.4 3-hydroxy-2naphthoic acid 9.2 117.9 12. 44,4dihydroxydiphenyl- 9. 2

n1ethane 3,3-dicarbpxy11e (535Methylenedisaheyclic ac 12. 4Ethylenediamine salieylate. $1.2 8G. 3 12.4 .do 14.4 .10 U

solved cupric oxide was recovered, washed and dried and reweighed todetermine the amount of cupric oxide which had dissolved. The followingtable shows the results obtained:

Copper oxide solubility (percent by weight Weight ratio,

(percent EDA/SA by weight) E thyleuediamine (percent by weight) 5IBmCDGOOHHH bhKlioho $M Samples of reagent grade cuprous oxide wereplaced in 52 grams (50 ml.) solutions of the following composition at200 The data will be best understood by reference to the curves. All ofthe curves plot the number of grams of cupric oxide which is soluble asthe ordinate, but they have different abscissae.

FIG. I shows the results obtained in an experiment where 1 gram ofcupric oxide was present and the treating solution involved 6.75 gramsof ethylenediamine, 42.5 grams of water and various additions ofsalicylic acid as shown by the abscissa. The experiment was carried onfor hours at 200 F., and it will be noted that there is a rapid rise inthe quantity of cupric oxide dissolved with additions of salicylic acidup to about 4 grams of salicylic acid.

FIG. la for the same experimental conditions plots as abscissa theweight ratio of ethylenediamine to salicylic acid. It is noted that thisrises very rapidly and then descends somewhat less rapidly, but there isa hump in the intermediate range which reaches a peak at about a ratioof 1.3.

FIG. 2 for the same test conditions otherwise employs 2,4-dihydroxybenzoic acid instead of salicylic acid and plots as abscissathe weight ratio of ethylenediamine to 2,4-dihydroxybenzoic acid. Itwill be noted again that there is a hump in this case at a weight rationof 1.2.

FIG. 3 employs similar test conditions except that the sodium salt ofsalicylic acid is used and the abscissa is the weight ratio ofethylenediamine to the salicylic acid sodium salt. It will be noted thatthis is very ineffective and evidently does not have properties similarto the composition of ethylenediamine and salicylic acid.

FIG. 4 plots as abscissa the weight ratio of ethylenediamine to5,55'-methylenedisalicylic acid. This is very effective and shows a humpat about the weight ratio of 1.2. The other conditions in this test arethe same as for FIG. 1.

FIG. 5 for similar test conditions employs ethylenediamine salicylateand ethylenediamine. The abscissa is the weight ration ofethylenediamine to ethylenediamine salicylate and the curve has a peakat about 1.

FIG. 6 is a test performed using a solution having 1 gram of cupricoxide, 42.5 grams of water, and 7.5 grams of sodium hydroxide withvarious quantities of ethylenediamine salicylate. The test time was 5hours at 200 F. The abscissa is the weight ratio of sodium hydroxide toethylenediamine salicylate. It will be noted that this composition iscompletely ineffective and therefore the good results do not seem to bea matter of alkalinity imparted by ethylenediamine. However, it isnecessary that the aqueous compositions of this invention be of alkalinecharacter in order to dissolve the salicylic acid which is essentiallyinsoluble in water which is not alkaline.

Tests made at a temperature of approximately 72 F. on a wide range oftotal concentrations and weight ratios of salicylic acid in aqueoussolutions of ethylenediamine showed complete solubility of the salicylicacid and that the solutions were alkaline. The results of these testsare shown in the following table:

pH of Selected Aqueous Solutions of Ethylenediamine (EDA) and Salicylictriethylenetetramine and tetraethyleneopentamine in place ofethylenediamine, and similarly for their use with salicylic acid or thepreviously mentioned alternative therefor.

FIG. 7 for test results similar to FIG. la has substituted 3-hydroxy-Z-naphthoic acid for salicylic acid. The abscissa is the weightratio of ethylenediamine to 3-hydroxy-2-naphthoic acid. This compositionis quite effective and shows a hump at a weight ratio of about 1.

FIG. 8 has test conditions similar to FIG. la except thatlhydroxy-2-naphthoic acid has been used instead of salicylic acid andthe abscissa is the weight ratio of ethylenediamine tol-hydroxy-2-naphthoic acid. This composition is quite ineffective.

FIG. 9 shows results obtained using 3 grams of cupric oxide, 42.5 gramsof water, 6.75 grams of ethylenediamine and 5.0 grams of salicylic acid,the abscissa in this case showing time. The quantity of cupric oxidedissolved rises steeply at first and then becomes almost asymptotic tothe horizontal.

FIG. 10 shows a test made with 1 gram of cupric oxide per 50 grams ofsolution in the presence of ethylenediamine and salicylic acid held at aweight ratio of 1.4. The test was carried on for 5 hours at 200 F. andthe abscissa shows the percentage of ethylenediamine by weight. It willbe noted that the curve rises sharply and uniformly. Experimentsindicate that this weight ration is the most effective for combinationsof ethylenediamine and salicylic acid.

A composition of the character described above in reference to FIG. 10at 12.5 percent of ethylenediamine by weight was used experimentally ata power station to remove copper oxide from four drain coolers whichcould not be diassembled for mechanical cleaning and had not beencleaned for over 20 years. Approximately 275 pounds of copper oxide wereremoved from an area totaling 4,500 square feet.

About 4 years later two of these four drain coolers were againexperimentally cleaned, comprising a preliminary application ofapproximately 5 percent inhibited hydrochloric acid to remove ironoxides, then a water rinse and finally treatment with the samecomposition used for the original cleaning. Approximately 350 pounds ofcopper oxide were removed from an area totaling 2,250 square feet,representing substantial improvement in rate of copper oxide removal.For the more Continued QUANTITY OF CUPRIC OXIDE DISSOLVED BY SOLUTIONSHAVING REAGENTS NOTED Weight Weight percent oi-- Solution peasant of c CA d ompoom ou rie oxi e Number Component A nent A Component B non? Bdissolved 110 .d 11.9 o-Hy droxybenz oic acid 13.2 37.0 17 do 11.9Ethylonediamine selicylate. 1'3. 2 77.0 ..d0 11.95,5methylenedisalicyclic 13. 2 18.0

acid.

Experiments were carried on using the composition of the H 0.0000 0.00000.0000 0.0000 invention for cleaning a copper catalyst of the typeemployed 1 in an oxidation bomb for determining Oxidation Stability of 1Special New Mineral Insulating Oils Containing 2,6-d1-tert1ary-buty1-1mm"; X 0,0002 0.0001 0.0000 0 paracresol by Rotating Bomb, ASTMspecification D21 12-62T, and Continuity of Steam-turbine Oil OxidationStability by Rotating Bomb, ASTM specification D2272-64T. H Instead ofcleaning the catalyst with sodium cyanide solution as specified in thesespecifications, the composition of the invention was used andcomparative pressure gage charts were' obtained comparing cleaning by acyanide (in this case potassium cyanide) and by composition 23. Theresults obtained are very comparable showing that the composition of theinvention is effective for this service.

Comparative studies were made on the corrosion of various alloys bycomposition 23 above referred to. The following table shows the analysesof the materials tested.

\ Stress corrosion tests were made using U-bends of average dimensions3%inches long, one-fourth inch wide and one-sixteenth inch thick, theother procedure being the same except that the rest was run for 161hours. The U-bends were mounted horizontally on vertical glass supports,each specimen separated from the adjacent one by a glass separator. Dueto space limitations only one sample was run of the carbon steel andCode Nos. A and B. Test results are designated B.

Chro- Molybmium Iron Carbon denum Vanadium Nickel Tung- Alusten minumNiobium Others .I bput'ial 111001101X l Maximunn 2 Ti (approximate).

Corrosion rates were determined for the various alloys in composition23. Disc lkinches in diameter and one-sixteenth inch thick with a centerhole of one-fourth inch were made. Seven hundred fifty ml. of thecomposition was used at a temperature of 200 F. and the test was run forI66 hours. The composition was placed in a 1,000 ml. glass reactionkettle equipped with a reflux condenser and a thermometer. The kettlewas placed on a constant-temperature bath. Various samples were mountedon a vertical glass rod separated by spacers of polytetrafluoroethylene.Three sets of samples were employed. At the end of the test the sampleswere removed, immersed in a mild detergent in an ultrasonic bath, thenrinsed with water followed by acetone and were dried and weighed. Testresults are called A.

Stress Corrosion Tests B Crevice galvanic corrosion data was run usingdiscs of linches diameter, one-sixteenth inch thick having a center holeof one-fourth inch and end squares lXl inch, one-sixteenth inch thickwith a center hole of onefourth inch. The procedure followed was similarexcept that that the time of test was 168 hours. Three galvanic couplesconsisting of a disc and a square specimen were mounted on a verticalglass rod, each couple being separated by a polytetrafluoroethylenespacer. Test results are designated C.

Crevice Galvanic Corrosion Tests C.

Corrosion lhs./ft./day

CODE A (square) 0.0130 C (disc) 0.0187 E (square) 0.0134 J (disc) 0.0137A151 1035 (square) 0.0418 H (disc) 0.0251

Corrosion rates of various materials and alloys upon con centration andvaporization of the solvent were also determined using the discs. Thetemperature of 200 F. was maintained until the samples were dry and thenthe temperature was raised to 500" F. One disc was placed horizontallyin a 100 ml heukri 'llunolvclll was introduced and the assembly wastttnlttlnlttrd m 200" l-' until the evaporation ol'the solvent wascomplete and then the beaker and sample were placed in an oven at 500 F.until complete removal of the residue had occurred after which thesamples were evaluated as below described. Test results are designatedas D.

Concentration and vaporization Tests D Having thus described ourinvention what we claim as new and desire to secure by Letters Patentis:

1. A process of dissolving copper oxide, by applying thereto an alkalineaqueous solution comprising (1) a polyamine selected from a groupconsisting of ethylenediamine, diethylenetriamine, triethylenetetramine,and tetraethylenepentamine, (2) a compound selected from a groupconsisting of salicylic acid, metahydroxybenzoic acid,parahydroxybenzoic acid, a dihydroxybenzoic acid, 5-5'-mcthylcnedisalieylic acid, 3-hydroxy-2-naphthoie acid, salts thereofwith a polyamine selected from said first-mentioned group and saltsthereof with ammonium hydroxide, and (3) balance water, the totalconcentration of the polyamine of the first-mentioned group and thecompound of the second-mentioned group being between 0.25 andsubstantially 100 percent by weight, and the ratio by weight of thepolyamine of the first-mentioned group to the compound of thesecond-mentioned group being between about 0.25 and 6, forming awater-soluble complex with copper ions.

2. A process of claim 1, in which said ratio by weight of the polyamineof the first-mentioned group to the compound of the second-mentionedgroup is between 0.50 and 4.

3. A process of claim 1, in which the concentration of the polyamine ofthe first-mentioned group plus the compound of the second-mentionedgroup is between 1 and 50 percent by weight.

4. A process of claim 3, in which the ratio of the weight of thepolyamine of the first-mentioned group to the compound of thesecond-mentioned group is between about 0.50 and 4.

5. A process of dissolving copper oxide, by applying thereto an alkalineaqueous solution comprising ethylenediamine plus salicylic acid, thebalance being water, in a total concentration of ethylenediamine andsalicyclic acid between 0.25 and substantially percent by weight andwith a weight ratio of ethylenediamine to salicylic acid of betweenabout 0.25 and 6, forming a water-soluble complex with copper ions.

6. A process of dissolving copper oxide, by applying thereto an alkalineaqueous solution comprising ethylenediamine plus salicylic acid, thebalance being water, the weight ratio of ethylenediamine to salicylicacid being about 1.4 and the concentration of ethylenediamine plussalicylic acid being between 1 and 50 percent by weight, forming awater-soluble complex with copper ions.

7. A process of dissolving copper oxide, which comprises applyingthereto a solution of ammonium hydroxide and ethylenediamine salicylate,the balance being water, the quantity of ammonium hydroxide plusethylenediamine salicylate being between 1 and 50 percent by weight andthe concentration of ammonium hydroxide being sufficient to maintain thecomposition alkaline.

ii. A process of dissolving copper oxide, which comprises applyingthereto a solution of ammonium hydroxide in the presence of a salicylateof a polyamine selected from a group consisting of ethylenediamine,diethylenetriamine, triethylenetetramine and tetraethylenepentamine, thebalance being water, the total quantity of ammonium hydroxide plus thesalicylate of the polyamine being between 0.25 and substantially 100percent by weight, the quantity of ammonium hydroxide being sufficientto maintain the solution alkaline.

9. An alkaline aqueous solution for dissolving copper oxide,

which essentially consists of l) a polyamine selectedfrorn a groupconsisting of ethylenediamine, diethylenetriamine,

triethylenetetramine and tetraethylenepentamine, and (2) a compoundselected from a group consisting of salicylic acid, metahydroxybenzoicacid, parahydroxybenzoic acid, a dihydroxy-benzoic acid,55-methylenedisalicylic acid, 3- hydroxy-Z-naphthoic acid, salts thereofwith a polyamine selected from said first-mentioned group and saltsthereof with ammonium hydroxide, (3) the balance being water, the totalconcentration of the polyamine of the first-mentioned group plus thecompound of the second-mentioned group being between 0.25 andsubstantially 100 percent by weight, the weight ratio of the polyamineof the first-mentioned group to the compound of the second-mentionedgroup being about 0.25 and 6, forming a water-soluble complex withcopper ions.

10. An alkaline aqueous solution of claim 9, in which the totalconcentration of the polyamine of the first-mentioned group and thecompound of the second-mentioned group is between 1 and 50 percent byweight.

11. An alkaline aqueous solution of claim 9, in which said weight ratiois between 0.50 and 4.

12. An alkaline aqueous solution for dissolving copper oxide, whichessentially consists of a solution of ethylenediamine and salicylic acidin a concentration range of ethylenediamine plus salicylic acid ofbetween 0.25 and substantially 100 percent by weight, the balance beingwater, in which the weight ratio of ethylenediamine to salicyclic acidis between about 0.25 and 6, forming a water-soluble complex with copperions.

13. A composition of claim 12, including a mild abrasive and athickening agent, in the form of a paste for cleaning and polishingbrass and copper.

14. A composition of claim 12, in combination with a gaseous foamingagent sufficient to produce a foam having a foamto-liquid ratio in therange of from 7 to l to 30 to 1 15. An alkaline aqueous solution ofclaim 12, in which said weight ratio is about 1.4.

16. A composition for dissolving copper oxide, essentially consisting ofammonium hydroxide, a salicylate of a polyamine selected from a groupconsisting of ethylenediamine, diethylenetriamine, triethylenetetramineand tetraethylenepentamine, the balance being water, the totalconcentration of ammonium hydroxide plus the salicylate of the polyaminebeing between 0.25 and substantially 100 percent by weight, the quantityof ammonium hydroxide being sufficient to maintain the compositionalkaline.

17. A composition for dissolving copper oxide, which essentiallyconsists of ammonium hydroxide, ethylenediamine salicylate and water,the total concentration of ammonium hydroxide being sufficient tomaintain the composition alkaline.

2. A process of claim 1, in which said ratio by weight of the polyamineof the first-mentioned group to the compound of the second-mentionedgroup is between 0.50 and
 4. 3. A process of claim 1, in which theconcentration of the polyamine of the first-mentioned group plus thecompound of the second-mentioned group is between 1 and 50 percent byweight.
 4. A process of claim 3, in which the ratio of the weight of thepolyamine of the first-mentioned group to the compound of thesecond-mentioned group is between about 0.50 and
 4. 5. A process ofdissolving copper oxide, by applying thereto an alkaline aqueoussolution comprising ethylenediamine plus salicylic acid, the balancebeing water, in a total concentration of ethylenediamine and salicyclicacid between 0.25 and substantially 100 percent by weight and with aweight ratio of ethylenediamine to salicylic acid of between about 0.25and 6, forming a water-soluble complex with copper ions.
 6. A process ofdissolving copper oxide, by applying thereto an alkaline aqueoussolution comprising ethylenediamine plus salicylic acid, the balancebeing water, the weight ratio of ethylenediamine to salicylic acid beingabout 1.4 and the concentration of ethylenediamine plus salicylic acidbeing between 1 and 50 percent by weight, forming a water-solublecomplex with copper ions.
 7. A process of dissolving copper oxide, whichcomprises applying thereto a solution of ammonium hydroxide andethylenediamine salicylate, the balance being water, the quantity ofammonium hydroxide plus ethylenediamine salicylate being between 1 and50 percent by weight and the concentration of ammonium hydroxide beingsufficient to maintain the composition alkaline.
 8. A process ofdissolving copper oxide, which comprises applying thereto a solution ofammonium hydroxide in the presence of a salicylate of a polyamineselected from a group consisting of ethylenediamine, diethylenetriamine,triethylenetetramine and tetraethylenepentamine, the balance beingwater, the total quantity of ammonium hydroxide plus the salicylate ofthe polyamine being between 0.25 and substantially 100 percent byweight, the quantity of ammonium hydroxide being sufficient to maintainthe solution alkaline.
 9. An alkaline aqueous solution for dissolvingcopper oxide, which essentially consists of (1) a polyamine selectedfrom a group consisting of ethylenediamine, diethylenetriamine,triethylenetetramine and tetraethylenepentamine, and (2) a compoundselected from a group consisting of salicylic acid, metahydroxybenzoicacid, parahydroxybenzoic acid, a dihydroxy-benzoic acid,5-5''-methylenedisalicylic acid, 3-hydroxy-2-naphthoic acid, saltsthereof with a polyamine selected from said first-mentioned group andsalts thereof with ammonium hydroxide, (3) the balance being water, thetotal concentration of the polyamine of the first-mentioned group plusthe compound of the second-mentioned group being between 0.25 andsubstantially 100 percent by weight, the weight ratio of the polyamineof the first-mentioned group to the compound of the second-mentionedgroup being about 0.25 and 6, forming a water-soluble complex withcopper ions.
 10. An alkaline aqueous solution of claim 9, in which thetotal concentration of the polyamine of the first-mentioned group andthe compound of the second-mentioned group is between 1 and 50 percentby weight.
 11. An alkaline aqueous solution of claim 9, in which saidweight ratio is between 0.50 and
 4. 12. An alkaline aqueous solution fordissolving copper oxide, which essentially consists of a solution ofethylenediamine and salicylic acid in a concentration range ofethylenediamine plus salicylic acid of between 0.25 and substantially100 percent by weight, the balance being water, in which the weightratio of ethylenediamine to salicyclic acid is between about 0.25 and 6,forming a water-soluble complex with copper ions.
 13. A composition ofclaim 12, including a mild abrasive and a thickening agent, in the formof a paste for cleaning and polishing brass and copper.
 14. Acomposition of claim 12, in combination with a gaseous foaming agentsufficient to produce a foam having a foam-to-liquid ratio in the rangeof from 7 to 1 to 30 to
 1. 15. An alkaline aqueous solution of claim 12,in which said weight ratio is about 1.4.
 16. A composition fordissolving copper oxide, essentially consisting of ammonium hydroxide, asalicylate of a polyamine selected from a group consisting ofethylenediamine, diethylenetriamine, triethylenetetramine andtetraethylenepentamine, the balance being water, the total concentrationof ammonium hydroxide plus the salicylate of the polyamine being between0.25 and substantially 100 percent by weight, the quantity of ammoniumhydroxide being sufficient to maintain the composition alkaline.
 17. Acomposition for dissolving copper oxide, which essentially consists ofammonium hydroxide, ethylenediamine salicylate and water, the totalconcentration of ammonium hydroxide plus ethylenediamine salicylatebeing between 0.25 and substantially 100 percent, the quantity ofammonium hydroxide being sufficient to maintain the compositionalkaline.